As a position controller aiming at a high speed response, for example, a position controller is available, which is provided with a command generator for generating position instructions, a position control unit for controlling a position by inputting a position instruction and the position of a motor being an object to be controlled, and outputting a speed instruction so that they become coincident with each other, a speed control unit to control a speed by inputting a speed instruction and a speed of the motor, and outputting a torque instruction so that they become coincident with each other, and a current control unit for controlling a current on the basis of the inputted torque instruction, and further provided with a subtracter which obtains a speed deviation by subtracting the speed from the speed instruction, an integrator which obtains an integral figure of the speed deviation by time-integrating the speed deviation with a time constant Ti, a multiplier for multiplying the speed instruction by .alpha.(0.0.ltoreq..alpha.1.0), an adder and subtracter which adds a signal of the multiplier to an integral figure of the speed deviation and at the same time subtracts the speed therefrom, a multiplier for multiplying an output of the adder and subtracter by a speed loop gain, and a torque filter for filtering a signal of the multiplier through a low-pass filter and making it into a new torque instruction.
However, there is such a problem by which in cases where the speed loop gain is increased or where the time constant is shortened, the control system itself may be likely to vibrate by delay of the torque filter consisting of a low-pass filter secured to suppress vibrations induced by the mechanical system.